This is a grant for support of 4 three week workshops which are given at Cold Spring Harbor Laboratory on the following subjects: Molecular Biology and Developmental Genetics of Drosophila; Yeast Genetics; Molecular Cloning of Eukaryotic and Viral Genes; Transformed Cells and Teratocarcinomas. This supplement requests funds for the addition of a fifth workshop of two weeks duration entitled: Animal Cell Culture in Serum Free Medium.